at 9:30 this morning, the nation observed a moment of silence to mark one week since the tragedy in newtown, connecticut. church bells rang out, one for each victim and two more for the shooter and his mother. >>> in washington, the president marked the moment, bowing his head in the oval office. within hours, another kind of silence was broken with the powerful national rifle association's defiant new message. here's abc's senior justice correspondent, pierre thomas. >> the nra has blood on its hands! shame on the nra! >> reporter: the nra leader had barely begun when protesters blamed the powerful lobby for the nation's epidemic of gun violence. >> nra, stop killing our children! >> reporter: but the nra was defiant. after remaining silent in the wake of the worst elementary school shooting in the nation's history, wayne lapierre was on the attack, blaming others for the recent carnage. high on the list, violent video games. >> there exists in this country, a callous, corrupt, and corrupting shadow industry that sells and stows violence against its own people. >> reporter: nra officials i